The present invention relates to probes for imaging evanescent microwave fields. In some embodiments the present invention relates to achieving high Q values by using sapphire capacitors that are arranged in parallel. Additionally, the present invention relates to methods of making and using such probes. Furthermore, some embodiments relate to using such probes for microwave microscopy, and/or for imaging samples thereby.
Prior work in this area used a shunt series combination. Thus, the maximum Q was solely determined by the resistance of the series R-L-C probe equivalent circuit and tuning network. Additionally, prior methods used calculations based on capacitance arising from the gap between a spherical conducting tip and a perfectly conductive sample surface. As a result, such methods do not accurately predict how the probe reacts in the electric field between it and the sample.
In contrast to prevailing methods, the method of the present invention is independent of the electrical properties of the material. Thus, unlike the prior art, the present invention applies equally well to dielectrics, conductors and superconductors. Furthermore, the method of the present invention, as set forth herein, enables the solution of the classical electrodynamic boundary value problem concerning a superconductor modeled as a dielectric having a complex permittivity with a large negative real part, which can be associated with the persistent current. Still further, in some embodiments the resistance is cut by up to about 50% in comparison to prior microwave probes, which results in higher Q values and correspondingly high sensitivity. Thus, the present invention represents a significant advance in the state of the art.